Method of producing a protective coating on objects of magnesium or magnesium alloys



Patented Apr. E7, 1923.

CHRISTIAN BERGH BACKJER, OE BERGEN, NORWAY.

METHOD 0! PRODUCING A PROTECTIVE COATING 9N OBJECTS 01E MAGNESIUM ALLOYS.

No Drawing.

To aZZ whom it may concern:

Be it known that I, CuRIs'rIAN Baron BAcKEn, a subject of the King of Norway, residing at Bergen, Norway, have invented certain new and useful Improvements in Methodsof Producing a Protective Coating I on Objects of Magnesium or Magnesium Alloys; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertams to make and use the same.

This invention has for its object a method of treating objects or materials of magnesium or magnesium alloys so as to produce upon the metal a strongly adhering coating of substantial thickness. 1

According to the invention such coatings are produced from the metal itself by subjecting it to an oxidizing treatment, the 1ntensity and duration of which is adapted to the thickness of the coating to be roduced.

The coatin is suitably produce by subjecting the o jects or materials, which may consist of magnesium or a magnesium alloy I or which may only have a surface layer of such metal or alloy-to the action of water or water vapour at a temperature above 100 C. This treatment may be carried into effect under ordinary or raised ressures.

By such a treatment it is possi le to obtain a compact strongly adhering coating of ma nesium hydroxide, the thickness of whlc 1 may be controlled by suitable variations in the temperatures employed and in the duration of the treatment.

As an example may be mentioned that'by heating an ob ect of magnesium in an autoclave under a steam-pressure of about 10 atmospheres in 15 minutes a coating of about 1.5 mm. thickness has been obtained and by boiling in about one hour under a ressure of about 5 atmospheres a coating of a out 0.2-

mm. thickness has been produced.

The coating is an electrical insulator and possesses great resistanceagainst the action of the constituents of the atmosphere. The

present process is therefore adaptable to the Q Application filed December 1a, 1921. Serial No. 522,941.

be wound in place advantage be subjected to the described treatment in the finished a paratus or the conductors may first be rovided with a thin layer of the coating, W ereupon they may and finally provided with desired thickness. Insulaa coating of the be produced from magnesium tors may alloys or other methods, whereupon they may be subjected to the described treatment.

The coating produced in the described manner resists the influence of chemically acting substances, for example salt solutions and the like and magnesium or magnesium alloys provided with the same coating may therefore be employed where such substances are present, for example in sea water (for example for crank cases and the like for ship motors).

It is known to efi'ect the insulation of aluminium conductors by providing the same with a coating of aluminium hydroxide. As compared with such aluminium hydroxide coatings, the coating of magnesium hydroxide produced according to the present invention is fundamentally different in several respects for example therein that the produced in any desired.

coating may be thickness, so that it is applicable also for high tension currents.

The coating is hard and tough and of great cohesive power and it is strongly adering so' that it does not fall off when the objects are subjected to mechanical strain. By means of im regnation for example with water glass so utions during or after the process of producing same, the strength of the coating ma be increased and its character may be a tered, When impregnation with water glass is made use of a subsequent treatment with an acid will be suitable.

The described method may also be employed for the production of objects which all through consist of magnesium hydroxide, the oxidizing treatment of the shaped object being in this case continued until the entire metal is converted. Tn this case the objects may beforehand have been shaped of massive metal or for example of a powder of the metal or alloy.

As is well known magnesium metal when boiled in water under ordinary pressure hemagnesium by stamping or byv which comprises comes covered with a layer of magnesium hydroxide. This layer is, however, so thin that it is unmeasurable with a micrometer, and no method was known, whereb a layer of a thickness above 0.01'mm. coul be produced.

I claim:

1. Method of producing a coating upon objects and materials of magnesium and magnesium alloys which comprises heating of the objects in the presence of water at a temperature of above 100 C. y

2. Method of treating objects and materials of magnesium or magnesium alloys heating the objects under a superatmospherical pressure at a temperature above 100 C. in the presence of water and continuing this treatment until the magnesium metal of the object has been converted into an oxygenous magnesium compound to a depth of at least 0.01 mm.

3. Method of treating materials and objects of magnesium or magnesium alloys to produce an electrically insulating coating ythereupon which comprises heating of the objects under a pressure of several atmospheres at a temperature above 100 C. in the resence of water.

4. Method of producing an electrically insulating coating upon the windings of transformers, motors. and other electrical apparatus'according to claim 1 which comprises producing a thin layer upon the conductors before winding, then bringing the conductors into position and then subjecting the formed object to the oxidizing treatment until a coating of desired thickness has been produced.

5. Objects and materials of magnesium or magnesium alloys havin a hard adhering coating of a thickness 0 at least 0.01 mm. comprising an oxygenous magnesium compound, produced from the metal itself.

In testimony that I claim the foregoing as my invention,-I have signed my name in presence of two subscribing witnesses.

CHRISTIAN BERGH BACKER.

Witnesses:

J OHN KRAMME, S. A. Anrmnsrm, 

